Eye color

The genetics of eye color, like hair color, are still being worked out, and it's clear that several genes can modify the eventual outcome. In a population sense, it should be noted that all populations except Caucasians basically have brown eyes, while amongst Caucasians one categorization that researchers track is blue vs non-blue.

One gene with a significant role in determining blue eye color is OCA2, a gene with variants first linked to albinism and perhaps melanoma risk.

The following OCA2 variants, all located in the first intron of the gene, have been linked to blue eye inheritance; together, they form a haplotype that occurs in 90% of individuals seen with blue or green eye color, but can also be seen in 10% of individuals with brown eye color. [PMID 17236130]

More recently, one potentially functional OCA2 SNP that is part of a 13 SNP haplotype covering 166kB located at the other side of the gene has been found in 97% of individuals with blue eye color [PMID 18172690]: